Plastic article in situ molded to a porous substrate

ABSTRACT

An article of manufacture comprises a molded-plastic fitment such as one of the halves of a snap fastener molded in situ to a porous substrate such as a garment fabric. Various embodiments are described for the article, as well as dies for forming the same, and methods and a machine for making the same.

This application is a continuation of copending application Ser. No.427,720 filed Oct. 27, 1989, (now abandoned) and said copendingapplication is a continuation of application Ser. No. 314,772, filedFeb. 23, 1989 (now abandoned); and said application Ser. No. 314,772 isa continuation of application Ser. No. 062,968, filed Jun. 17, 1987 (nowabandoned); said application Ser. No. 062,968 is a division of originalapplication Ser. No. 889,880, filed Jul. 28, 1986 (now U.S. Pat. No.4,735,753). Application Ser. No. 063,019, filed Jun. 17, 1987 (now U.S.Pat. No. 4,784,591) is also a division of said original application.

BACKGROUND OF THE INVENTION

The invention relates to functional devices and their attachment totextile or other substrate material, as for example snap fasteners forarticles of clothing, disposable garments, and the like.

Conventional methods of attaching a functional part to a substrate orfoundation material usually involve the two separate steps of (a)fabricating the functional part as a discrete item, and (b) attachingthe functional part to the substrate or foundation material. Attachmentcan utilize a surface effect, as via an adhesive, welding, brazing, andsoldering; or the substrate can be pierced to accommodate threaded,riveted or swaged projections, or the like.

The invention is regarded as applicable to a wide variety offunctional-attachment situations but to simplify-present description,the context of use of the invention will primarily concern "snapfasteners", employed as detachable closure devices in the apparelindustry. Such snap fasteners have come in many varieties, but they areillustrative of conventional practice requiring prefabrication ofdiscrete parts, usually of steel, brass, or plastic resin, the samebeing attached to fabric by piercing and joining to a companion part, or"cap".

Current technology involves the fabrication of snap fasteners as aseparate operation, in a first industry or manufacturing facility; thefabricated fastener parts are supplied to another industry ormanufacturing facility where fastener parts are manipulated in relationto a fabric and are then attached to the fabric. A typical fastenerconsists of a "set" of four parts, as shown in FIG. 1, namely, asindicated by legend, stud and socket parts which are separablyengageable by snap fit, and a cap part for securing each of the stud andsocket parts to its particular garment region. When the four-partfastener is of molded plastic, the snap action of separable engagementis occasioned by compliantly yielding interference as the bulbous studtraverses the entrance to the hollow of the socket; when such a fasteneris of metal, the yielding interference is realized by segmenting thesocket geometry into individual spring fingers, or by the use of wirerings or other compliantly deformable shapes.

The operative stud and socket parts of FIG. 1 are shown securable tofabric via cap prongs which pierce the fabric, but this is but one ofvarious fabric-piercing cap techniques which are conventional, forexample, metal caps with projecting eyelet, prong-cage or stapleformations, or molded-plastic caps with projecting post or prongformations. In every case, four parts must be separately fabricated, thefabric must be pierced, and an upsetting, curling or swaging operationis needed to clinch the cap and operative fastener part so as tosandwich its fabric foundation.

Quality of attachment is of key importance in producing a satisfactoryfastener, and most development work in the industry has been directedtoward obtaining more secure attachment to the substrate; for example,it is a common practice to fold the fabric into several layers ofthickness, with insertion of one or more layers of reinforcing material,to provide better integrity for the sandwiched cap-secured stud orsocket part. But with repeated engagement/disengagement cycling of thefastener, lateral forces tend to pull or tear the fabric through the"sandwich". Tightly woven cotton and blend fabrics are more resistant totear, while synthetic knits and solid sheets are more readily damaged.Metal snaps can be tightly clinched to create a clamping action, or"pinch", on the fabric. But a pinching clamp is not readily achievablewith plastic fastener parts, due to inherent resilience of the plasticmaterial.

The need for four parts in a snap-fastener "set" has created anaesthetic requirement. The industry has decorated the non-functionalparts (i.e., caps) with designs and geometries to enhance appearance onthe face side of the garment. In some cases, design orientation isimportant, thus dictating another positional or orientation requirement.

The attachment of snap fasteners requires special machinery, whichvaries in complexity, from simple foot-operated presses to electricallyor pneumatically driven units which automatically feed, orient andattach a stud or socket part to its companion cap, eyelet, staple orprong. The operator inserts and-locates the garment and triggers themachine, which feeds the active part on one side, the inactive part onthe other, and clinches them together. Further sophistication involvesfeeding the garment through the machine automatically, and attachingmultiple snaps. These machines are usually leased to the user on anannual basis, and must be serviced by trained mechanics. Attachingmachines now on the market are not readily converted to other sizes ortypes of fasteners. In many cases, a seasonal garment requirement callsfor short use and is then left idle, while the leasing cost continues.

Cost is a primary factor for relevant comparison of the presentinvention. Typical four-part metal snap fasteners range in price from$40.00 to $100.00 per thousand sets, and plastic fasteners range from$15.00 to $50.00 per thousand sets.

The current market for snap fasteners is believed to be in the order of$100 million annually in the United States, and to several times thisfigure worldwide, it being understood that these figures include cost ofthe products as well as leasing costs of the machines to assemble them.The major application is to apparel; other and lesser applicationsinclude footwear, tarpaulins, luggage, envelopes, and appliance andmachine panels.

BRIEF STATEMENT OF THE INVENTION

It is an object of the invention to provide an improved method and meansfor attaching a functional device, such as a snap fastener, to asubstrate such as a fabric material, avoiding most of the operationaland material elements of cost and complexity which characterize presentpractice.

Another specific object is to provide a method and means for in situforming and attachment of a snap fastener or other functional device toa substrate.

Another specific object is to provide an improved method of attaching adevice of the character indicated to a substrate with greater anchoringeffectiveness than heretofore, in the sense that anchoring effectivenessis distributed on a substrate-area and volumetric basis and is thus lesslikely to induce tearing or other degradation of the substrate to whichit is attached.

It is also a specific object to meet the above objects without requiringprefabrication of parts and wherein, in the case of snap fasteners, theoption is available to make the attachment with little or no externallyvisible indication of the fact of attachment.

A further specific object is to meet the above objects with a methodwhich lends itself to simple and rapid changeover, from onefunctional-device attachment style and/or size, to another.

A general object is to meet the above objects as to snap fasteners,while also substantially reducing cost, and improving quality andreliability of the finished product and its attachment to the substrate.

The invention in a preferred embodiment achieves the foregoing objectsby in situ plastic molding of a functional device while also attachingthe same by local impregnation of porous substrate material. Morespecifically, a measured quantity of plastic material, such as a plasticpellet, is of such volume as to accommodate (1) compressionalimpregnation of the full thickness of the substrate, from one side ofthe substrate and against a reacting anvil (or die) at the oppositeside, and (2) die-forming of the functional device at said one side,once the impregnation is complete. Compressive liquifying energy isimparted to the plastic by ultrasonic modulation of continuousdisplacing force applied normal to the substrate and to the anvil, andboth the impregnation and the die-forming phases of the process areaccomplished in a single-stroke cycle of the displacing force.

DETAILED DESCRIPTION

The invention will be described in detail, in conjunction with theaccompanying drawings, in which:

FIG. 1 is an exploded perspective view of the four separate componentparts of a representative prior-art snap-fastener set, wherein each ofthe parts is captioned, and stud-related parts are inopposed-perspective relation to socket-related parts;

FIG. 2A is an enlarged sectional view of the stud formation of one partof a snap-fastener embodiment of the invention;

FIG. 2B is a view similar to FIG. 2A for the coacting socket formationof the other part of the same snap-fastener embodiment of the invention;

FIG. 2C is a view similar to FIG. 2B to show an alternative socketformation having snap-engageability to the formation of FIG. 2A;

FIGS. 3A to 3G are successive simplified vertical sectional views toillustrate a typical sequence of events in formation of the parts ofFIGS. 2A and 2B;

FIGS. 4A, 4B, 4C, and 4D are simplified alternative die relationshipsfor performing the method of the invention;

FIG. 5 is a simplified diagram to illustrate cooperating elements of amachine for in situ manufacture of stud and socket formations as inFIGS. 2A, 2B, 2C;

FIG. 5A is a schematic diagram of a velocity-control and tip-elevatingdetail applicable to the machine of FIG. 5;

FIGS. 6A, 6B, 6C, 6D, 6E and 6F are successive vertical sectional viewsto illustrate the sequence of events in formation of stud and socketparts with the machine of FIG. 5;

FIG. 7 is a multi-level diagram to illustrate coordination of variousindividual functions in a single cycle of operation of the machine ofFIG. 5; and

FIG. 8 is a simplified view in side elevation to show an article ofmanufacture embodying the invention.

It has been explained above that the four separately manufactured andlabeled component parts of FIG. 1 are representative, of prior artpractice in respect to snap-fasteners. The showing happens to be for aplastic injection-molded variety in which the multiple prongs 10 of afirst cap part must pierce a substrate such as garment fabric beforeentry into, passage through and deformed clamping over registeringapertures 11 in the base of a stud part. Similarly, the prongs 10' of asecond cap part must pierce another substrate area before entry into,passage through and deformed clamping over registering apertures 11' inthe base of a socket part. The two thus-equipped substrate areas arethen separably securable by snap action via stud entry into and removalfrom the socket, relying upon transient locally compliant deformation ofone or both of the stud and socket formations.

In contrast to the prior art, FIGS. 2A and 2B respectively show a studformation 12 and a cooperable socket formation 14, both according to theinvention. The stud formation 12 is of suitable plastic material, moldedin situ to and through an intervening porous substrate 15, which happensto be shown as a fabric, folded over to be double thickness atintegration with stud formation 12; the socket formation 14 is similarlyassembled to a porous substrate 15'.

The technique of forming at 12 will be later described, but it sufficesfor present purposes to state that the main body of formation 12 is thatregion which lies within an outer diameter D and in which the plasticmaterial of formation 12 has fully impregnated all voids of thesubstrate and has become a solid integrated component of the substrate.The stud itself is shown as a relatively thin stubby annulus 16, risingto an extent H₁ above a relatively thin base plastic layer 17 whichlocally covers the substrate face to which stud 16 is applied. At theother face of the substrate, a similar relatively thin base layer 18 ofplastic covers the substrate but in the form shown is peripherallyintegrated with and reinforced by a shallow circumferentially continuousand rounded outer rim 19, of inner diameter D₂.

The stud annulus 16 is characterized by a circumferentially continuousconvex bulbous and bead-like outer contour 20, and its radial thicknessΔR₁, in the context of elastic properties of the involved plasticmaterial, is such as to provide the stud annulus 16 with a degree ofrelatively stiffly but smoothly compliant local deformability, in thecourse of snap-on/snap-off transient interference coaction with thesocket formation 14 of FIG. 2B. For such coaction purposes, the outerdiameter D₃ of the stud annulus 16 exceeds the throat diameter D₄ of theradially inward bead-like contour 21 of a relatively thin stubby annulus22 of the socket part 14; this annulus 22 rises to the extent H₂ above arelatively thin base layer 23 of plastic locally covering the substrateface to which socket 14 is applied.

Preferably, H₁ is equal to or slightly less than H₂ so that, when stud12 is engaged to socket 14, a flat flange-like surface 26 ringing thebase of the stud annulus 20 will have circumferentially continuouscompliantly clamped seating engagement with a flat land surface 27 whichis the upper limit of the socket formation 14. Preferably also, theeffective radial thickness ΔR₂ of the socket annulus 22 is such, in thecontext of the involved plastic material, that a degree of stifflycompliant deformability is realized in the course of snap-on/snap-offcoaction with the stud formation 12 of FIG. 2A.

As in the case of stud (12) integration with substrate 15, socket 14 isintegrated by solid impregnation through all pores of the substrate 15',within an outer diameter D₅, which is comparable with outer diameter D₁of the stud formation. And a circumferentially continuous and roundedouter rim 24 rings the thin base layer 25 which locally covers substrate15' within rim 24. Marginally compressed substrate material,peripherally surrounding each visible part of each plastic formation12-14, will be understood as a schematic suggestion of the compressiveaction of clamped opposing dies used in the in situ molding process, aswill be made more clear.

For most purposes, snap-on/snap-off coaction between thestud-characterized substrate 15 and the socket-characterized substrate15' will be perfectly satisfactory, especially if the substrate is agarment fabric and therefore relatively soft and compressible; in thatevent, the snap-fastener fabrics 15--15' will be in gap-free adjacency.However, if a more closely adjacent relation is desired, FIG. 2Cillustrates, for a sufficiently soft and pliable substrate 15", that asocket formation 14' may be the product of having locally offset andcompressed the substrate material in the course of the in situ moldingprocess. Thus, in FIG. 2C, the substrate is locally compressed at 30 toa thickness Which is about half normal thickness, and the center of thelocally compressed region 30 is also consolidated by plasticimpregnation into an axially depressed offset A from the central planeof symmetry of unimpregnated regions of substrate 15". The socketannulus, throat contour and like dimensions and relationships in thesocket formation 14' may be as described for FIG. 2B and therefore thesame reference numerals have been adopted, with primed notation, forcorresponding features.

It will be clear, by inspection of FIGS. 2A and 2C, that upon snap-inengagement of stud formation 12 to socket formation 14', the flangeregion 26 of formation 12 will develop a circumferentially continuousseating relation with the mating land surface 27' of socket formation14', and that upon this occurrence, adjacent surfaces of thesnap-fastened substrates 15--15" will be mutually engaged, and free ofany gap.

FIGS. 3A to 3F provide simplified illustration of successive steps inthe in situ formation of a stud 31 (FIG. 3F) in integrally unitedrelation to a two-ply substrate 32. As seen in FIG. 3A, coacting upperand lower dies 33-34 are in separated but vertically aligned relation,to allow for insertion and correct relative placement of the substratematerial 32. The lower die 34 is characterized by an annular clampingland 35, in vertically matching registration with a similar land 36 onthe characterized lower face of the upper die 33. Concentrically withinland 35, lower die 35 is characterized with a circumferentialrim-defining concavity 37, surrounding a depressed flat 38. The upperdie 33 has a central bore 39 sized and adapted for sealed reception andguidance of a ram 40; and, within the clamping land 36, a generallycylindrical cavity of depth H₃ has a circumferentially continuous sidewall 41 of undulating section designed to produce the bulbous convexcontour of the ultimately formed stud.

Having thus identified coacting features of the mold, it will beobserved that ram 40 is the cylindrical lower or tip end of anultrasonic converter 43, to be more fully described in connection withthe machine of FIG. 5; as will also become more clear in connection withFIG. 5, the tip 40 is subjected by the machine to controlled verticaldisplacement and, when subjected to ultrasonic excitation, the lowerface of tip 40 is axially oscillated, to impart relativelysmall-amplitude piston-driving impact on such material as it maycontact. The key material exposed to ultrasonic action is a preciselymeasured quantity of suitable plastic, which may be a single pellet 44positioned on substrate 32 and coaxial with the central axis of dies33-34 and of tip 40; alternatively, an additional precisely measuredpellet 44' may be similarly positioned on flat 38, beneath substrate 32.

As shown, pellet 44 (44') diameter is less than bore diameter at 39,thereby assuring clean entry of pellet 44 into bore 39 at the time (FIG.3B) when dies 33-34 are displaced into clamped position, wherein thematching lands 35-36 squeeze the substrate 32 to thereby limit theperimeter within which substrate pores are available for impregnation.In FIG. 3, it will be seen that the presence of lower pellet 44', in thecontext of a sufficiently flexible substrate 32, has upwardly displacedthe upper pellet into partial reception within bore 39, all in readinessfor the next step (FIG. 3C) wherein tip 40 is downwardly displaced intopellet (44) contact.

At or before pellet (44) contact, the ultrasonic converter 43 isactivated to induce the lower face of tip 40 into short-amplitudepiston-like reciprocation at ultrasonic frequency, as piston 40continues its overall descent to a limiting position (FIG. 3D) whereinnot only have all voids, pores and interstices of the substrate beenfilled but so also have all die-shaping surfaces been pressurized withpellet plastic which has been liquified by the heat ofparticle-to-particle friction resulting from ultrasonic piston action.In FIG. 3D, a double-headed arrow 45 will be understood to symbolize thevigorous action of short-stroke piston oscillation whereby the plasticis quickly heated to melting temperature so that substrate impregnationand mold filling can proceed to completion.

FIG. 3E is virtually identical to FIG. 3D, but it depicts a short staticcondition or dwell for heat dissipation-through-the conductive coolingcapacity of die members 33-34 and tip 40, thus allowing the moldedplastic to solidify in its substrate-impregnated and mold-filling shape.Finally, FIG. 3F depicts the opening of molding dies, retraction of tip40, and the stripping of the upper molding die 33 from the bulbousformation of the newly created stud formation. In stripping, it isadvisable first to effect total withdrawal of tip 40 from the mold bore39, and then to drop the lower mold half 34, prior to performance of thestripping operation by an angular tipping of the molded region withrespect to mold die 33; an arcuate arrow 46 will be understood tosuggest such tipping.

FIG. 3G corresponds to FIG. 3E, in the sense that it shows a moldedsocket part, like the part 14 of FIG. 2B, just prior to retraction oftip 40 and downward separation of the lower mold half 34', therebypermitting the fabric 32' with its integrally molded socket part to beangularly tilted (as at 46 in FIG. 3F) in stripping the same from theupper mold half 33'. It will be noted that stripping is facilitated (1)by inherent compliant deformability of the molded-plastic material and(2) by the inwardly tapered slope of the upper-mold wall 47 whichdefines the outer surface of the molded-socket formation, it beingfurther noted that the uppermold half 33' provides a continuouscylindrical bore for accommodation of tip 40, all the way to itsdownward extreme position (as shown in FIG. 3G) and that a dependingannulus 48 within the upper-mold cavity is relied upon to define thethroat contour of the socket-part opening.

In the discussion thus far, it has been presumed that the "cap" side ofa given in-situ molding to substrate shall be a rounded bead or ridgesurrounding a thin flat covering of the involved face of the substrate.But this is by no means a requirement, as examination of the studformations of FIGS. 4A to 4D will reveal, it being understood thatfeatures of these different alternatives are also applicable as featuresof corresponding socket-formation parts.

In FIG. 4A, the upper mold half 50 is essentially as described for moldhalf 33 in FIG. 3, but the lower mold half 51 has a cavity 52 of uniformdepth, being characterized by a rounded peripheral edge and a flatbottom. The uniform depth will be understood to enable the otherwiseflat bottom of the cavity to be decoratively or otherwise uniquelycharacterized for creation of an intaglio or relief design in the moldedproduct, e.g., to make the face molded by bottom 52 appear with aninitializing letter, a button design, or otherwise.

In FIG. 4B, the same upper mold half 50 is used in conjunction with alower mold half 52 which presents a flat anvil-like upper face in totalregistration with the flat annular rim 54 of the upper mold half 50,whereby clamp action of mold halves 50-53 in squeezing compression ofsubstrate 15 defines lateral confines of plastic impregnation of thesubstrate, with little or no plastic surface formation at anvil contact.Thus, if the color of the impregnating plastic is a substantial match ofthe color of the substrate, the plastic of the molded stud of FIG. 4Bwill be essentially unobservable at the exposed face 55 of thesubstrate.

In FIG. 4C, the same upper mold half 50 appears with a differentanvil-like lower mold half 53', wherein the anvil face which confrontsthe face 55 of the substrate is characterized by a pattern of recesses56. This may be a pattern of individual dome-forming recesses that arespaced over the area confined by annular clamping of the substrate.Alternatively, the plural recess sections shown in FIG. 4C may representplural ring-forming recesses that are concentric about a centraldome-forming recess 56. The result in the molded product is anillustrative local decorative appearance on the face side 55 of thesubstrate.

FIG. 4D is illustrative of the fact that the fastener-side of the moldedproduct does not necessarily have to be on the side from which the ramand ultrasonic action of tip 40 are applied. Thus, in FIG. 4D, tip 40and its associated upper mold half 57 are applied to the face side 55 ofthe substrate, and the lower mold half is characterized by astud-defining cavity 59. In the process of making a molded product, asuitably sized and measured plastic pellet, applied to the substrateface, prior to mold closure, and prior to descent of tip 40, can serveboth for substrate impregnation and for lower-mold filling;alternatively, upper and lower measured plastic charges may be inserted,as in the case of FIG. 3A. The product may be completed by sopremeasuring the plastic charge that when tip 40 is flush with the clampland 60, all accessible substrate voids have been filled, and so alsohas the lower-mold cavity 59, under requisite pressure for forming andinitial-curing purposes; alternatively, with a slightly shorter measureof plastic, the substrate face 55, at the stud formation, will be aslightly indented circular area, formed by tip 40. Still furtheralternatively, with a slightly greater measure of plastic, the substrateface 55, at the stud formation, will be a slightly raised or thickenedcircular coverage of the substrate face, the same being attributable tothe bore diameter of mold half 57.

FIG. 5 schematically shows functional components of a machine forproducing in-situ molded functional devices of the above-describedcharacter, under control of a suitably programmed microprocessor 65. Themachine will be understood to include means (not shown) for properlyorienting and positioning substrate material 15 between upper and lowermold halves 66-67, which are shown to have molding-cavity shapesgenerally as described for die parts 33-34 of FIGS. 3A to 3E. The uppermold half 66 may be a selectively removable fitting to a bracket 68 butfor simplicity is shown integrally formed therewith. Bracket 68 is partof a slide 69 which is guided for vertical reciprocation underdisplacement actuation by a double-acting pneumatic positioning cylinder70. A sensor 71 electrically tracks the instantaneous position ofbracket 68 (and therefore also of mold half 66) and transmits positiondata via a feedback line 72 to the control microprocessor 65. Apneumatic controller 73 operates from a suitable source of fluidpressure to determine the extent and direction of up/down displacementof upper die 66, via actuator 70; and an electrical control for thispurpose will be understood to receive its control signals from an outputconnection to microprocessor 65, as suggested by the legend "To 73". Insimilar fashion, another microprocessor output carries the legend "To75" to indicate similar double-acting displacement control (at 75) of asecondary double-acting pneumatic actuator 74, via a pneumaticcontroller 75; actuator 74 is mounted to bracket 68 and has up/downpositioning control of a stripper arm 76 having hinge connection at 77to bracket 68.

The lower die element 67 is shown to be replaceably mounted to asupporting member 78 which is up/down displaceable in vertical guidewaysunder actuating control which may be similar to that described for theupper-die actuator 70 and its controller 73. The double-headed arrow 78'will be understood to indicate such actuation and control, as determinedby another microprocessor output, labeled "To 78".

Thus, when and as dictated by microprocessor sequencing, the respectivedie halves 66-67 may be driven into squeezing (clamping) contact withsubstrate, and retracted singly or in unison, as may be appropriate forthe particular involved molding operation.

In similar fashion, but preferably under positioning control by ahydraulic system, a double-acting cylinder 80 has actuating connection81 to a vertically guided slide 82 which mounts the ultrasonic converter43. A motor-driven pump 84 draws hydraulic fluid from a reservoir 85 tosupply a proportional valve 86 having connections to the respective endsof cylinder 80, and the magnitude and direction of resultingdisplacement of the ultrasonic converter 43 are subject to theelectrical control dictates of microprocessor 65, via control connection87, instantaneous position feedback being electrically provided to themicroprocessor by a sensor 88 of slide (82) position. As shown, driverstructure of the ultrasonic converter 43 is carried by a bracketcomponent 89 of slide 82; from this point, booster (90), horn (91) andtip (40) components of the ultrasonic system are vertically suspendedfrom the driver structure, and requisite power-supply energy is appliedto the driver structure by suitable means 92 having a control connection93 from microprocessor 65.

In the form shown, precisely measured pellets 44 of plastic to be moldedare formed by a shear device 94 which accepts incremental feed ofplastic rod 95 in the guide bore of a fixed block 96 having anelectrical heater winding for initial softening of downwardly fed rod95. A horizontally reciprocable shear plate 97 has a rod-receivingopening which, in the retracted position of plate 97, registers with thebottom or discharge end of the bore of block 96; in this position, thethickness of shear plate 97 determines the incremental length of rod 95which can be fed (as suggested by an arrow 95'), to a fixed stop 98. Andit will be understood that, at the proper instant in the cycle ofmachine operation, namely, when tip 40 is fully retracted and die parts66-67 have closed or are in the process of closing on substrate 15, adouble-acting pneumatic actuator 99 imparts horizontal displacement ofplate 97, to the right, in the sense of FIG. 5, shearing off a newpellet 44 and transporting the same into registry (phantom outline 97')for gravitational release into the bore of the upper mold half 66; thisis quickly followed by retraction of shear plate 97, to the positionshown in solid outline, the reciprocation displacements being suggestedby a double-headed arrow 99'. Again, it will be understood that thereciprocation of shear plate 97 may be under microprocessor control, andschematic indication of this fact is provided by a microprocessor outputconnection having the legend "To 99". Similarly, the incremental feed ofplastic rod 95 may also be under microprocessor control, but the arrowdesignated 95' will be understood to indicate positive feed, as by feedrolls (not shown) under the constant urging of a stalled-torque electricmotor drive, the drive being effective to impart the incremental feedingadvance of plastic rod only when shear slide 97 returns to its retractedposition after having just dropped a freshly sheared pellet 44 into thebore of the upper mold half 66. Once the rod has been incrementally fedto stop 98, continued rod-feeding force will be understood to place theheating tip of the rod under such axial compression as to assure a cleanshearing cut, perpendicular to the rod axis.

The schematic detail of FIG. 5A illustrates a velocity-control featuregoverning actuated descent of the tip 40 in the course of a moldingprocess, as well as a transient tip-lifting feature to free tip 40 frompellet contact at the time of initiating its ultrasonic excitation. Thearrangement is seen to comprise a rod connection from vertical-slidepart 81 to a piston in a first fixedly mounted cylinder A. Rate-controlhydraulic elements B-C and a solenoid valve A' are interposed betweencylinder A and a second cylinder D, the latter having a "floating"piston to accommodate a changing volume of hydraulic fluid in its upperzone, against the reaction of a spring (not shown) and/or compressed airin its lower zone. The hydraulic part of this system additionallycomprises the head-end zone of cylinder A, as well as solenoid valve A'and the rate-control elements B-C; these elements are shown as anadjustable orifice (B) and as a check valve (C), connected in paralleland oriented to govern (i) an adjustably "slow" rate of tip (40) descentin the course of a molding operation and (ii) an otherwise unrestrainedretracting displacement of tip 40. The solenoid valve A' will beunderstood to be under control of microprocessor 65, based ondisplacement sensing at 71 and 88, and to be operative to establish aprecisely determined fixed stop, against advance of tip 40 beyond itspredetermined stop position. A further solenoid valve E will beunderstood to admit a transient supply of compressed-air to the lowerzone of cylinder D, under timed control by microprocessor 65, assuggested by the legend "To E" in FIG. 5, all for a purpose to beexplained in connection with FIGS. 6 and 7.

Having identified principal operating components of the machine of FIGS.5 and 5A, a representative machine cycle of operation will be described,the same being under position-sensing, timing, and sequencing control bymicroprocessor 65. In this connection, the sequenced operation of apreferred mold and stripper will be described for successive sectionalviews of FIG. 6, taken with the diagram of FIG. 7, which depicts a full2π cycle of the machine, in context of its π/2 quadrants.

In the mold configuration of FIGS. 6A to 6E, stud-defining contours arethe product of coacting cavities of two annular die elements 101, 102,the upper (101) of which is removably mounted to a bore 103 in bracket68, and the lower (102) of which is a removably fitted part of thestripper arm 76. These die elements separably fit at frusto-conicalinterface between their respective convex and concave mating surfaces,when the stripper arm is in its normal raised (unactuated) position(FIGS. 6A to 6D). The parting line between cavities of die elements 101,102 is such that the cavity of upper element 101 is responsible for theouter bulbous contour of a stud formation (as at 20 in FIG. 2A), and thecavity of lower element 102 is responsible for the flat flange (as at 26in FIG. 2A) at the base of bulbous formation 20. Such a parting line isseen in FIG. 6E to enable stripper arm 76 to fully engage flange 26 whenstripping the bulbous formation 20 (with transient compliantdeformation, as shown) from the upper die element 101, it beingunderstood that stripping of the molded stud from die element 102involves similar transient compliant deformation of bulbous feature 20as substrate 15 is pulled away, by means not shown.

Above its molding-cavity portion, the upper die element is characterizedby a cylindrical guide bore 104 with a tapered lower end whichterminates in close clearance relation with the outer cylindricalsurface of ultrasonic tip 40. An elastomeric seal member 105, suitablyof Teflon, is contoured to fit the lower end of guide bore 104; and aflanged bushing 106, guided by the upper end of bore 104 and inclearance with tip 40, will be understood to be a means of tightlysealing the upper-end closure of the mold, at fit to tip 40 whilemolding pressure is operative. Downward arrows 107 in FIG. 6C will beunderstood to suggest application of such pressure during the moldingand curing phases of the process.

FIG. 6A further shows a presently preferred technique of pellet 44delivery to the molding system, being shown at the instant at which atransversely shiftable wedge 108 on a part 97' of shear plate 97 hasbeen actuated (by means suggested by double arrow 109) from its phantomposition 108' to the position at which it has elevated a new pellet 44slightly above the upper surface of the shear plate 97; this elevationwas achieved via a stop pin 110 that tracks wedge 108 and is guided bythe pellet bore of plate 97, it being understood that for the phantomposition 108', pin 110 determines the vertical extent for shearedformation of pellet 44.

The sequence depicted in FIGS. 6A to 6E begins with FIG. 6A as an eventin the fourth quadrant ##EQU1## of FIG. 7, namely when a new pellet 44has been shorn from rod 95 and has been advanced forward to registrybeneath tip 40 (and slightly elevated toward tip 40). This shear-plateevent is depicted at curve (h) of FIG. 7 and is seen at curves (a) and(e) to lap a brief period of ultrasonic excitation and downwarddisplacement of tip 40 into sufficiently tacky contact with the uppersurface of pellet 44 to enable its retrieval from shear plate 97 andwithdrawal into the upper mold-cavity region, as depicted in FIG. 6B forthe end of the last quadrant of the cycle of FIG. 7; at this time, FIG.6B also shows that the pellet-delivery system has been retracted, clearof all molding operations.

Having retracted the pellet-delivery system, the mold halves may beclosed to squeeze against opposite sides of the substrate 15; FIG. 6Cshows this relationship in the further context of applying pressure(107) to the seal closure 105 while tip 40 is advanced in the moldingand curing process. More specifically, the curves (a) and (b) of FIG. 7show concurrent timing of tip (40) advance and mold-half clampingforces, extending for approximately half the total cycle, and lappingthe first, second and third quadrants of the cycle. In response to thesedisplacement forces, tip 40 is restrained in its advance, by reason ofthe adjustment at orifice B (FIG. 5A). However, once the mold halveshave clamped to squeeze the substrate, and just prior to supplyingultrasonic power to the driver 43 of tip 40 (see curve (e) of FIG. 7),seal 105 is subjected to compressional force (see curve (d) of FIG. 7);and solenoid valve E is briefly opened for such transient lifting of tip40 as to strip pellet 40 from its tack engagement to tip 40, therebyaffording maximum opportunity for prompt establishment of theultrasonic-piston mode of tip 40 action. Thus, at the instant whencontrolled descent brings tip 40 into pellet-engaged action against thesubstrate, tip 40 is in full ultrasonic axial-displacement oscillation;and the sonic-melting, substrate-impregnation and mold-filling phaseproceeds in the further course of the adjustably controlled descent oftip 40. This descent abruptly ceases when microprocessor 65 ascertains,from its tracking of position sensors 71-88, that the predeterminedlimiting advance of tip 40 has been achieved, thereby activating thehydraulic-stop solenoid valve A' of FIG. 5A; as can be seen from curves(f) and (e) of FIG. 7, this abrupt stop occurs after cut-off ofultrasonic power for a brief instant to permit tip 40 to exert pure(unmodulated) axial force while consolidating the filled condition ofthe mold and of the substrate region within the perimeter of mold-clampaction.

Curve (j) of FIG. 7 illustrates timing for cooling means (not otherwiseshown) which is operative upon die and/or tip (40) elements, should thematerials and molded-article size require cooling, in aid of curing, andfor reduction of overall cycle time; normally, however, special coolingprovision is not needed because tip 40 and its massive suspensionprovide a good heat sink. Once curing has sufficiently advanced, with orwithout special cooling, seal (105) compression is relaxed (curve (d))and the hydraulic-stop valve A' is opened, to allow the mold-opening andtip-retraction strokes indicated for curves (b) and (a) of FIG. 7. FIG.6D illustrates that retraction of tip 40 precedes mold-opening. And FIG.6E illustrates stripper-arm actuation, which, for the case of studmolding may be coincident with mold-opening, and which for the case ofsocket molding (see dashed lines indicated by legend in curves (a) and(c) of FIG. 7) is preferably after mold-opening, for a reason to beexplained in connection with FIG. 6F.

Remaining curve (i) of FIG. 7 will be seen to apply for timing ofrod-feeding means which relies upon the stalled-torque motor drivereferred to in connection with reference numeral 95' of FIG. 5. In thiscurve (i) alternative, the feed means is operative to maintainstalled-torque force application to the rod while a pellet is sheared;thereafter, at the beginning of the third quadrant of the cycle, thestalled-torque motor is reversed to retract the end of the rod formomentary reheating within the heated device 94.

FIG. 6F is illustrative of the two-part upper-mold concept inapplication to the molding of a socket part 115 to substrate 15. Thedriving end of tip 40 is characterized by a necked and bulbous formationwhich accounts for the inner contour of the molded part 115, and, forease of stripping, the lower end of the bore of upper-die element 101'is flared outward. The dashed-line portions of curves (a) and (c), inthe context of the mold-opening even of curve (b) of FIG. 7, showpreference for opening the mold halves so that tip 40' will drive themolded product clear of the flared portion of upper-die element 101'(see FIG. 6F) before stripper arm 76 (curve (c)) is actuated, to partthe product from tip 40'. Thereafter, as shown by the dashed line ofcurve (a), tip 40' is returned to its retracted position.

In discussion above, ultrasonic action on pellet plastic has beendescribed as liquification by the heat of particle-to-particle frictionresulting from ultrasonic piston action. This is undoubtedly true and issometimes referred to as "internal hysteresis", but my observations todate suggest that the pellet melts progressively, from the substrate up,in that initial pellet engagement with the substrate comprises manypoint contacts, each of which is a small-area of energy focus, for localinitiation of melting. The inherent result of melting from the substrateup is to assure an impregnating, void-filling liquid resin presence andflow, literally at and throughout the substrate, as long as theultrasonic action continues.

Having described several embodiments for different facets of myinvention, it is helpful to enumerate certain observations, based onexperimental use of the invention to date:

1. The resin used for pellet 44 is presently preferred to be supplied insolid unit form, as described for rod 95, in order to achieve maximumproduct quality and minimum cycle time. Powders or granules melterratically, and their volume is difficult to control. The most genericform of solid resin is extruded rod, which can be cut into preforms orpellets.

2. An accurate pellet can be sheared from rod material, when:

a) The bores of the shear (97) and guide die (94) are close-fitting tothe rod diameter;

b) The rod is heated to or slightly below its softening point; and

c) A moderate axial force is imparted to the rod, against the feed stop(98, 110), while shearing.

3. The amount of resin, e.g., height of the pellet (44) is critical andmust be accurately controlled. This value must be matched to the type ofsubstrate, thickness, number of substrate layers, type of fastener, andresin type.

4. The pellet (44) must be centered, i.e., on the same axis as the tip(40), to achieve uniform melting.

5. The pellet diameter should not exceed the tip diameter, and it ispreferably less than the tip diameter. Any overhang of the pelletoutside the contact circle of the tip (40) will result in incompletemelting.

6. Penetration velocity of the tip (40) must be controlled. Too high avalue causes flash and poor adhesion to the substrate. Too low a valueaffects integrity of the substrate and burns the resin. Ideally, avariable profile of velocity is desirable in the course of a givenstroke, starting relatively high and ending relatively low as the moldfills.

7. The amplitude of ultrasonic oscillation is somewhat critical. Largevalues provide good adhesion but can cause burning; too low a valueresults in poor adhesion. A profile that starts high and ends low isideal, in the course of the period of application shown at curve (e) ofFIG. 7, and lapping the first and second quadrants of the cycle.

8. Initial pellet height is critical. Too tall a pellet causes pooradhesion, but enables provision of desirable aesthetics on thenon-functional side; too short a pellet allows the tip (40) to come tooclose to the substrate, causing damage.

9. A small amount of tip overtravel, after sonic action ceases, isdesirable. This "packs" the mold and prevents flash past the seal (105).

10. A definite stop (A, A'), to halt tip (40) against further advance,is essential for a quality product.

11. The resilient seal (105) must be able to withstand oscillation ofthe tip (40). To my knowledge, the best material is Teflon, which canhave tight squeezing engagement around the tip (40), without damage.

12. Seal life can be enhanced by (a) squeezing the seal only whilemelting the resin, (b) never allowing the tip to leave the seal (thusavoiding reentry problems), and (c) highly polishing the tip surfaces.

13. If a decorative design or cap is desired on the non-functional sideof the molded product, the anvil must provide distributed support of thesubstrate, as is provided by anvil 53' of FIG. 4C.

14. The type of resin used is not critical. Crystalline materials, suchas acetol or nylon, tend to flash more readily because they exhibit asharp melt point. Amorphous materials do not flash as readily but dorequire more energy to flow and to impregnate the substrate.

15. Resin alloys work well. The ultrasonic action causes violent mixingand produces homogeneous material. This fact enables use of scrap whichcontains several different base materials.

16. Typical cycle times are:

a. Melt time: 0.20 to 0.50 second.

b. Cool time: 0.50 to 1.50 seconds.

The described invention will be seen to achieve all stated objectivesand to provide advantages over existing technology, including:

1. Simultaneous creation and attachment of functional parts tosubstrates by melting plastic resins.

2. Use and application of ultrasonic energy to provide both the thermalaction and as a mechanical aid to mold-filling.

3. Total elimination of any need for discrete parts that must beprefabricated and then attached.

4. Preservation of substrate integrity during attachment.

5. Superior and very secure attachment of the formed part to thesubstrate, the impregnated region of the substrate becoming asignificant integrally formed structural component.

6. The option of making an attachment that is virtually invisible at thenon-functional face of the substrate.

7. The ability to rotationally and consistently orient any design orappearance feature on the nonfunctional side of the substrate, by virtueof the fixed orientation of the tooling.

8. The relatively short interval of time for a full cycle (FIG. 7)needed to melt, form and attach a part to substrate material.

9. The relatively simple and ready convertability of the process todifferent sizes, styles and types of parts and geometries.

10. Significantly reduced cost to manufacture an attached part, ascompared to discrete parts that must be manufactured separately.

11. The ability to attach to virtually any substrate that is porous orwill weld to the resin.

12. The ability to employ any from a wide range of thermoplasticsoffering a variety of properties.

13. Extremely short residence time of resin at molten temperatures, thusavoiding thermal degradation.

14. Elimination of runner systems normally required in the molding ofplastic parts, thus avoiding scrap production and recycling of regrind.

15. Total impregnating saturation of a porous substrate with the resin.

16. Ability to force resin through a porous substrate for mold-fillingon both sides of the substrate.

17. Ability to sense the current position of the tip (40) with respectto the upper mold, and to use the sensed information for precise cut-offof ultrasonic-energy supply.

18. Applicability of the process to full automation, with programmedin-line indexing of substrate material between successive moldingcycles.

19. Ability to accommodate a variety of substrate materials, ofdifferent thickness and in single or multiple ply.

20. The ability to use filler materials and/or reinforcing fibers (e.g.,glass-fiber flock) with the resin, to produce strong heat-resistantparts.

21. Relative insensitivity, allowing wide ranges in pressure, resinquantity and substrate variations.

22. Repeatability of the process, resulting in exact duplication ofsuccessively made parts attached to substrates.

23. Ability to strip finished product from the molds, in spite ofundercut mold formations.

24. The ability to mold unusual variations of common articles and toattach the same to substrates in oriented fashion, for example snapfasteners of square, triangular or oval appearance.

25. The ability to readily vary snap action in snap fasteners bychanging mold and/or tip elements.

26. The ability to use generic extruded rod as the resin source, thusemploying an economical, readily available material, and enabling acompact and clean delivery system.

27. Inherent adaptability to use of cold molds, thus enabling shortcycle times and virtually instantaneous melting of the preform (pellet)within the mold.

While the invention has been shown and described for variousembodiments, it will be appreciated that the invention may be modifiedand extended to other embodiments without departing from the scope ofthe invention. For example, and as illustrated by FIG. 8, the inventionlends itself to a specialized subassembly, involving separate elongatesubstrate tapes 120-121 of flexible porous (e.g., woven) material, towhich snap-fastener components have been molded. As shown, thesnap-fastener components 122 in distributed array at spacings D alongtape 120 are of stud variety, and the snap-fastener components 123 insimilarly spaced array along tape 121 are of socket variety. The twotapes are salable in snap-fastened array, but are separable, as forsewing as appropriate to garment parts which are to be separablyfastenable.

What is claimed is:
 1. As an article of manufacture, a unitarysingle-piece snap-fastener stud having a central axis of symmetry andin-situ molded to an unapertured portion of porous substrate from asolid pellet of plastic material, said stud having a functional studformation at one axial end and having a mounting base at its other axialend; said functional stud formation being a circumferentially continuouscup-shaped annulus that is open in the direction away from the base end,and the outer surface of said annulus having a convex bead at axialoffset from the base end and within the axial span of the annulus, thebead region of said annulus having stiffly compliant deformability uponinterfering snap-action fit to and removal from a mating snap-fastenersocket, said molded stud being the product of compressive deformation ofthe pellet in contact with the substrate and under such ultrasonicmodulation of continuous force normal to the substrate as to create manypoint contacts each of which acts as a small area of energy focus forlocal initiation of melting engagement of the solid pellet with thesubstrate in full-thickness solidly consolidated impregnation of thesubstrate over the area of said mounting base, and said mounting baseextending over the area within a perimeter which peripherallycontinuously surrounds said functional stud formation.
 2. In combinationwith the stud article of claim 1, a second article of manufacture,comprising a unitary single-piece snap-fastener socket havinginterfering snap-action mating fit to and removal from said studarticle, said socket having a central axis of symmetry and in situmolded to an unapertured second portion of porous substrate from anothersolid pellet of plastic material, said socket having a functional socketformation at one axial end and having a socket-mounting base at itsother end; said functional socket formation being a circumferentiallycontinuous cup-shaped socket annulus that is open in the direction awayfrom its socket-base end, and the inner surface of said socket annulushaving a convex bead at axial offset from the socket-base end and withinthe axial span of the socket annulus, the bead region of said socketannulus having stiffly compliant deformability upon interferingsnap-action mating fit to and removal from said snap-fastener stud, saidmolded socket being the product of compressive deformation of said otherpellet in contact with said second substrate portion and under suchultrasonic modulation of continuous force normal to said secondsubstrate portion as to create many point contacts each of which acts asa small area of energy focus for local initiation of melting engagementof said other solid pellet with the substrate in full-thickness solidlyconsolidated impregnation of the substrate over the area of saidsocket-mounting base, said socket-mounting base extending over the areawithin a perimeter which peripherally continuously surrounds saidfunctional socket formation.
 3. The combination of claim 2, wherein saidsnap-fastener stud and said snap-fastener socket are on substrates thatare first and second elongate tapes of flexible porous material, whereinsaid snap-fastener stud is one of a distributed and spaced array offirst snap-fastener studs each of which is molded from a different solidpellet of plastic material to one side of said first tape, and whereinsaid snap-fastener socket is one of a plurality of a correspondinglydistributed and spaced array of snap-fastener sockets of plasticmaterial, each of said sockets being molded from a different solidpellet of plastic material to one side of said second tape.
 4. Thearticle of claim 3, additionally including at the other side of eachsaid substrate a plastic cover of the impregnated pores associated witheach of said studs and sockets, each said cover being also formed fromthe pellet material of the stud or socket with which it is associated,and each said cover being integrally connected with its associatedmolded snap-fastener stud or socket via pore-impregnating plasticmaterial of one and the same pellet.
 5. The article of claim 3, in whichsaid tapes are preassembled via mutually detachable engagement ofcorrespondingly spaced mating studs and sockets.
 6. The article of claim1, in which said substrate is of flexible material.
 7. The article ofclaim 1, in which said substrate is part of a garment.
 8. The article ofclaim 1, in which said substrate is a composite of multiple plies withmelted material of said pellet solidly impregnating the pores of saidmultiple plies.